Abstract
This research is a theoretical investigation of the transient operation of a fluid-mechanical device known as a pumping ring. The purpose of this device is to pump small amounts of fluid from a lower to a higher pressure region and to serve as a fluid tight seal between the two regions. This device was patented by Verbeek (U.S. Patent 3,149,846) and has been used in the Philips Stirling Engine. The device consists of a thin walled circular ring (the pumping ring) with an inside radial taper which is fitted on a straight rod (the pumping rod) of circular cross section. An O-ring seal, located "between the housing and the outer surface of the pumping ring, serves as a fluid tight seal separating two regions filled with lubricating oil. The inside radial taper of the pumping ring is several orders of magnitude less than the pumping rod radius. The fluid flow phenomenon is therefore essentially that of hydrodynamic lubrication. The pumping rod executes periodic reciprocating translator motion. As the rod translates in the pumping direction, large pressures are developed in the fluid film formed by the taper between the pumping ring and the pumping rod. This pressure causes the ring to expand radially, allowing high pressure fluid to be pumped under the ring. On the return stroke of the rod the pumping ring ideally acts as a pressure seal, since no hydrodynamic forces are developed which would cause the ring to open. ...
Zull, Lawrence Michael (1973). An elastohydrodynamic investigation of time dependent pumping ring operation. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -158502.